Ferroelectric Polarization Effect on Charge Trapping in HfO 2 FeFETs Examined via Random Telegraph Noise

Understanding charge trapping mechanisms and characterizing oxide traps in hafnium oxide (HfO_2)-based ferroelectric field-effect transistors (FeFETs) is essential for addressing long read-after-write (RAW) delays and limited endurance, two key challenges hindering their adoption. In this work, we employ random telegraph noise (RTN) measurements under varying programming and polarization conditions to investigate their impact on charge trapping. We find that introducing a preliminary negative (erase) gate voltage pulse before a positive (program) pulse significantly alters the observed RTN signal, suggesting that distinct trap energies or spatial locations are activated following erase. By contrast, RTN after a positive-only program pulse exhibits highly repeatable behavior. Analysis of capture and emission time constants enables the extraction of trap energies, consistent with previously reported values in similar devices. Finally, we discuss the inherent limitations of RTN for comprehensive trap characterization. These insights advance the understanding of defect behavior in FeFETs and their role in device reliability.